Dementia: A general term for a decline in cognitive ability severe enough to interfere with daily life. Alzheimer's disease is the most common cause of dementia.
Neurodegeneration: The progressive loss of structure or function of neurons in the brain, which occurs in diseases like Alzheimer's.
Amyloid plaques and neurofibrillary tangles: Abnormal protein deposits found in the brains of individuals with Alzheimer's disease. These deposits contribute to the destruction of brain cells.